In order to reduce the aerodynamic drag coefficient of a heavy van truck, three single-variable and one multi-variable composite drag reduction devices were designed based on the rear structure of the heavy van truck. The results show that among the three single-variable drag reduction devices, the inclination angle θ of the linear type drag reduction device has the greatest influence on the aerodynamic resistance coefficient of heavy vans truck, and the model has the best drag reduction effect when the inclination angle θ=20°, the aerodynamic drag coefficient is 0.7693, and the drag reduction rate is 7.64%. The radius R of the arc drag reducing device has the least influence on the aerodynamic drag coefficient. The multivariable composite drag reduction structure also has a good drag reduction effect. The study can provide a reference for the optimal design of the rear structure of related vehicles.

No abstract

The change of the milling force during the milling process will directly affect the machining accuracy of the cycloid gear. In this article, the milling force prediction model of the cycloidal gear is used to predict the milling force of the cycloid gear. The results show that when the spindle speed increases, the milling force gradually decreases; the milling force is also closely related to the feed speed, axis milling depth and radial milling width. With the increase of axial milling depth and radial milling width, the milling force gradually increases, but the magnitude of the increase is different.